大豆内生细菌的分离及其作用效果研究

为利用内生细菌促进大豆生长发育,从而获得环境友好型生物调控剂,从大豆种子中分离得到优势内生细菌,研究其对大豆生长和生理指标的影响。把大豆种子装入无纺布袋内,在土壤中埋藏10 d后取出,种子表面消毒后在灭菌培养皿中培养,在胚根周围分离得到8株内生细菌,通过初步筛选获得2株具有促生作用的优势内生细菌KC-1和MD12-2,经鉴定分别为侧孢芽孢杆菌（Brevibacillus laterosporus）和枯草芽孢杆菌（Bacillus subtilis）,具有产生长素（IAA）和溶解有机磷的能力。使用2.5×10⁷ cfu·mL^-1的KC-1和MD12-2菌液浸种,对种子萌发有着显著促进作用;盆栽试验表明,10×10⁷、5×10⁷ cfu·mL^-1的KC-1和MD12-2菌液浸种,大豆的生长量、叶绿素含量、根系活力、硝酸还原酶活性和根瘤固氮酶活性均显著增加（P<0.05）。

Isolation of Endophytic Bacteria in Soybean and Its Action Effect

In order to explore the use of endophytic bacteria to promote the growth and development of soybean and thus to obtain environmentally friendly bioregulators, the dominant endophytic bacteria were isolated from soybean seeds and their effects on the growth and physiological indexes of soybean were investigated. Soybean seeds were put into non-woven bags and buried in the soil for 10 days. After disinfection of the surface of the seeds, 8 strains of endophytic bacteria were isolated around the radicle, two dominant endophytic bacteria KC-1 and MD12-2 were obtained through preliminary screening. They were identified as Brevibacillus laterosporus and Bacillus subtilis, respectively. They had the ability to produce IAA and dissolve organic phosphorus. KC-1 and MD12-2 significantly promoted seed germination when the concentration was 2.5×10⁷ cfu·mL^-1. Pot experiment showed that the plant height, plant dry weight, chlorophyll content, root activity, nitrate reductase activity and nodule nitrogenase activity of soybean were significantly increased after soaking seeds with KC-1 and MD12-2 at the concentrations of 10×10⁷ and 5×10⁷ cfu·mL^-1 （P<0.05）.